<!DOCTYPE html>
<html lang="en">
<head>
	<meta charset="UTF-8">
	<title>固定盒子居中显示</title>
	<style type="text/css">
		body{
			margin: 0;
			padding:0;
		}
		.bbox{
			width: 1000px;
			height: 600px;
			background: #aaa;
			margin: 0 auto;
			position: relative;
		}
		.sbox{
			width: 600px;
			height: 100px;
			background: #666;
			position: absolute;
			bottom: 0;
			left: 50%;
			margin-left: -300px;
		}
	</style>
</head>
<body>
	<div class="bbox">
		<div class="sbox"></div>
	</div>
</body>
</html>